arb/acb_poly/zeta_series.c

130 lines
3.1 KiB
C

/*
Copyright (C) 2014 Fredrik Johansson
This file is part of Arb.
Arb is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "acb_poly.h"
#include "acb_dirichlet.h"
void
_acb_poly_zeta_cpx_series(acb_ptr z, const acb_t s, const acb_t a, int deflate, slong d, slong prec)
{
ulong M, N;
slong i, bound_prec;
mag_t bound;
arb_ptr vb;
int is_real, const_is_real;
if (d < 1)
return;
if (!acb_is_finite(s) || !acb_is_finite(a))
{
_acb_vec_indeterminate(z, d);
return;
}
if (acb_is_one(s) && deflate && d == 1)
{
acb_digamma(z, a, prec);
acb_neg(z, z);
if (!acb_is_finite(z)) /* todo: in digamma */
acb_indeterminate(z);
return;
}
is_real = const_is_real = 0;
if (acb_is_real(s) && acb_is_real(a))
{
if (arb_is_positive(acb_realref(a)))
{
is_real = const_is_real = 1;
}
else if (arb_is_int(acb_realref(a)) &&
arb_is_int(acb_realref(s)) &&
arb_is_nonpositive(acb_realref(s)))
{
const_is_real = 1;
}
}
mag_init(bound);
vb = _arb_vec_init(d);
bound_prec = 40 + prec / 20;
_acb_poly_zeta_em_choose_param(bound, &N, &M, s, a, FLINT_MIN(d, 2), prec, bound_prec);
_acb_poly_zeta_em_bound(vb, s, a, N, M, d, bound_prec);
_acb_poly_zeta_em_sum(z, s, a, deflate, N, M, d, prec);
for (i = 0; i < d; i++)
{
arb_get_mag(bound, vb + i);
arb_add_error_mag(acb_realref(z + i), bound);
if (!is_real && !(i == 0 && const_is_real))
arb_add_error_mag(acb_imagref(z + i), bound);
}
mag_clear(bound);
_arb_vec_clear(vb, d);
}
void
_acb_poly_zeta_series(acb_ptr res, acb_srcptr h, slong hlen, const acb_t a, int deflate, slong len, slong prec)
{
acb_ptr t, u;
hlen = FLINT_MIN(hlen, len);
t = _acb_vec_init(len);
u = _acb_vec_init(len);
if (acb_is_one(a))
acb_dirichlet_zeta_jet(t, h, deflate, len, prec);
else
_acb_poly_zeta_cpx_series(t, h, a, deflate, len, prec);
/* compose with nonconstant part */
acb_zero(u);
_acb_vec_set(u + 1, h + 1, hlen - 1);
_acb_poly_compose_series(res, t, len, u, hlen, len, prec);
_acb_vec_clear(t, len);
_acb_vec_clear(u, len);
}
void
acb_poly_zeta_series(acb_poly_t res, const acb_poly_t f, const acb_t a, int deflate, slong n, slong prec)
{
if (n == 0)
{
acb_poly_zero(res);
return;
}
acb_poly_fit_length(res, n);
if (f->length == 0)
{
acb_t t;
acb_init(t);
_acb_poly_zeta_series(res->coeffs, t, 1, a, deflate, n, prec);
acb_clear(t);
}
else
{
_acb_poly_zeta_series(res->coeffs, f->coeffs, f->length, a, deflate, n, prec);
}
_acb_poly_set_length(res, n);
_acb_poly_normalise(res);
}